P4 Flashcards
When do electrons become static?
When they are unable to flow through the medium, if it is an insulator.
What attraction occurs between items with a charge and items without a charge?
Positive attraction
Items with a charge attract to items which don’t have a charge.
What charge do electrons have?
Electrons have a negative charge
What is the attraction between opposition charges?
They attract each other / strong positive attraction
What is the attraction between the same charges?
They repel each other / strong negative attraction
What problems occur with static electricity?
- Attracts Dust
- Damages electronic components
- Cause shocks from door handles
What can be used to prevent sparks and allow static to discharge safely?
Earthing cables
What are the three main uses of static electricity?
- Painting
- Dust precipitators
- Defibrillators
How do paint sprayers work?
The nozzle of the paint gun is charged, causing the paint particles to also become charged. Because each paint molecule gets the same charge they repel away from every other paint particle. This causes the paint to land on the object evenly.
How do dust precipitators work?
In the chimney of a power station the dust particles gain a negative charge. The dust particles then induce a charge on earthed metal plates causing the plates to become negatively charged so the dust attracts to the plates
How do Defibrillators work?
Two paddles with insulated handles are connected to a power supply. These paddles are placed on the patients chest before being charged and then the current is released into the patient, causing the heart to contract
What is radioactive activity?
The number of radioactive particles a substance emits per unit of time.
What is half life?
How long it takes for a radioactive substance to half in mass.
How many particles of carbon 14 are found in living things?
1 part per ten million
What are the three main uses of Ultrasound?
- Ultrasound Scans
- Blood Flow
- Kidney Stone treatment